Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations establish the safety profile (not read-only, not destructive), and the description adds real context beyond them: the tool returns the upload plus its URL, and in app-capable hosts renders as an interactive panel that must not be re-serialized in the reply. The panel-rendering contract is substantive and not derivable from structured fields.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loads the core action, then the return, then the rendering caveat; each sentence carries information. The panel instruction is slightly digressive but genuinely necessary to prevent redundant output, so it earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema exists, and the description compensates by stating the return (the upload with its URL). Combined with annotations covering the mutation safety profile, an agent has what it needs to invoke and report this tool correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the schema already documents both blobName (from create_upload_url) and fileName (display name). The description only alludes to these indirectly and adds no syntax or format detail, so baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific action (add a file to the user's library) tied to the preceding create_upload_url flow, and names the resource precisely. An agent can distinguish this finalization step from upload_file and list_uploads without reading schemas.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Clearly roots the tool in the create_upload_url workflow and lists where the returned URL applies (create_post media, reference images, clipping input). It stops short of contrasting with the sibling upload_file, which an agent might reasonably confuse for the same job.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.